1. Field of the Invention
The present invention relates to a knit slide fastener having a row of continuous coupling elements knit into and along an element-supporting portion of one longitudinal edge of a knit fastener tape as the fastener tape is knit.
2. Description of the Prior Art
A conventional knit slide fastener disclosed, for example, in Japanese Patent Publication No. 38-11673 includes a fastener tape knit with threads of chain stitches and laid-in weft threads and having a longitudinal edge portion into and along which a nylon wire is laid to form a row of continuous coupling elements knit into the chain stitches as the fastener tape is knit. Another known knit slide fastener disclosed U.S. Pat. No. 5,035,125 includes a fastener knit with threads of chain stitches and a laid-in weft thread, and a row of continuous coupling elements formed from a plastic monofilament laid in and along one longitudinal edge portion of the fastener tape. At the longitudinal tape edge portion, the laid-in weft thread is interlaced with the chain stitches of two adjacent wales to urge the upper legs of the coupling elements downwards, and also with the chain stitches of a neighboring wale to urge the lower legs of the coupling elements downwards.
The conventional knit slide fasteners previously described are of the type including a fastener tape knit with threads of chain stitches and laid-in weft threads, and a plastic monofilament laid into one longitudinal edge portion of the fastener tape to form a row of continuous coupling elements knit into and along the one longitudinal tape edge portion. In the first-mentioned knit slide fastener, since the row of continuous coupling elements is restrained or bound by sinker loops of the chain-stitch threads of the ground structure, due to longitudinal stretch and contraction of the chain stitches, a desired dimensional stability is difficult to obtain. Because of this dimensional in stability, a smooth coupling engagement between two opposed rows of coupling elements is difficult to achieve. In the second-mentioned knit slide fastener, since needle loops of the chain-stitch threads are merely interlaced with the laid-in weft thread extending transversely across the longitudinal tape edge portion, wales composed of the chain stitches used to restrain or bind the legs of the coupling elements are readily stretchable in the longitudinal direction. Accordingly, like the first-mentioned knit slide fastener, the second-mentioned knit slide fastener is also dimensionally instable and cannot insure smooth coupling engagement between two opposed rows of coupling elements.